<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        .box1 {
            width: 400px;
            height: 400px;
            background-color: orange;

            /* 允许调整该元素的大小，必须配合overflow一起使用 */
            resize: both;
            overflow: hidden;
        }
    </style>
</head>
<body>

    <div class="box1"></div>
    
</body>
</html>